Five-port bistable pneumatic valve unit

ABSTRACT

THIS FIVE-PORT BISTABLE PNEUMATIC VALVE UNIT COMPRISING A BODY IN WHICH AN INLET PORT CONNECTED TO A SOURCE OF COMPRESSED GAS, FIRST AND SECOND OUTLET PORTS AND FIRST AND SECOND EXHAUST PORTS ARE FORMED, CHARACTERIZED IN THAT IT COMPRISES A CENTRAL FEED CHAMBER COMMUNICATING WITH SAID INLET PORT AND HAVING A FREE VALVE MEMBER SLIDABLY MOUNTED THEREIN, FIRST AND SECOND INTERMEDIATE OUTLET CHAMBERS BOTH CONNECTED ON THE ONE HAND THROUGH FIRST AND SECOND CONNECTING PASSAGES TO SAID CENTRAL CHAMBER, RESPECTIVELY, AND ON THE OTHER HAND TO SAID FIRST AND SECOND OUTLET PORTS, RESPECTIVELY, AND SAID FIRST AND SECOND EXHAUST PORTS, RESPECTIVELY, FIRST AND SECOND FLAP VALVES FREELY MOUNTED IN SAID FIRST AND SECOND INTERMEDIATE OUTLET CHAMBERS RESPECTIVELY FOR CLOSING SAID FIRST AND SECOND EXHAUST PORTS, FIRST AND SECOND PUSH MEMBERS DISPOSED EXTERNALLY OF SAID FIRST AND SECOND OUTLET CHAMBERS, RESPECTIVELY, AND REGISTERING WITH SAID FIRST AND SECOND EXHAUST PORTS SO THAT THEY CAN PROJECT THROUGH SAID EXHAUST PORTS AND UNSEAT SAID EXHAUST PORT FLAP VALVES WITHIN SAID OUTLET CHAMBERS, AND FIRST AND SECOND DEVICES FOR ACTUATING SAID FIRST AND SECOND PUSH MEMBERS RESPECTIVELY AND UNSEAT SAID FIRST AND SECOND FLAP VALVES RESPECTIVELY.

Oct. 26, 1971 R. METIVIER FIVE-PORT BISTABLE PNEUMATIC VALVE UNIT Filed Oct. 22, 1969 United States Patent O rm. (:1. nisc 1/08 US. Cl. 137119 7 Claims ABSTRACT OF THE DISCLOSURE This five-port bistable pneumatic valve unit comprising a body in which an inlet port connected to a source of compressed gas, first and second outlet ports and first and second exhaust ports are formed, characterized in that it comprises a central feed chamber communicating with said inlet port and having a free valve member slidably mounted therein, first and second intermediate outlet chambers both connected on the one hand through first and second connecting passages to said central chamber, respectively, and on the other hand to said first and second outlet ports, respectively, and said first and second exhaust ports, respectively, first and second flap valves freely mounted in said first and second intermediate outlet chambers respectively for closing said first and second exhaust ports, first and second push members disposed externally of said first and second outlet chambers, respectively, and registering with said first and second exhaust ports so that they can project through said exhaust ports and unseat said exhaust port flap valves within said outlet chambers, and first and second devices for actuating said first and second push members respectively and unseat said first and second flap valves respectively.

BACKGROUND OF THE INVENTION This invention is concerned with a five-port bistable pneumatic valve unit applicable notably to the construction of a double pneumatic oscillator.

Various bistable pneumatic devices are already known which can be used as fundamental or basic element in a pneumatic oscillator. Among these known devices conventional five-port distributors or bistable gates of the walleffect or Coanda effect are frequently used.

The conventional five-port distributor controlled by the fluid pressure is objectionable in that when it is used for constituting a pneumatic oscillator its tripping or reversing time is far from negligible if the control pressure is of the gradually varying type. To obtain a nearly instantaneous tripping, a sequence valve must be interposed between a time-lag device of the oscillator and the distributor control member for converting the progressive control pressure into a sudden, strong pressure pulse.

On the other hand, the wall-effect bistable gate requires a permanent output and therefore a considerable consumption of perfectly clean and dry gas, as well as an output amplifier.

SUMMARY OF THE INVENTION It is the essential object of the present invention to avoid the inconveniences of known devices bp providing a device of remarkably simple design.

To this end, this five-port bistable pneumatic valve unit comprising a body in which an inlet port connected to a source of compressed gas, first and second outlet ports and first and second exhaust ports are formed, is characterized in that it comprises a central feed chamber communicating with said inlet port and having a free valve member slidably mounted therein, first and second Patented Oct. 26, 1971 intermediate outlet chambers both connected on the One hand through first and second connecting passages to said central chamber, respectively, and on the other hand to said first and second outlet ports, respectively, and said first and second exhaust ports, respectively, first and second fiap valves freely mounted in said first and second intermediate outlet chambers respectively for closing said first and second exhaust ports, first and second push members disposed externally of said first and second outlet chambers, respectively, and registering with said first and second exhaust ports so that they can project through said exhaust ports and unseat said exhaust port fiap valves Within said outlet chambers, and first and second devices for actuating said first and second push members respectively and unseat said first and second flap valves respectively.

The push-member actuating devices may be of mechanical, pneumatic, hydraulic, electric or other type. Preferably, each push-member actuating device comprises a membrane associated with the corresponding push member and adapted to receive a control pressure for moving said membrane and the associated push member towards the relevant flap valve.

If the bistable valve unit of this invention is pneumatically operated it can function with an extremely progressive control pressure and can be triggered almost instantaneously. On the other hand, also in the case of a pneumatic actuation, this bistable unit is advantageous, in comparison with wall-effect bistable units, in that it consumes compressed gas only during the tilting operation proper.

This pneumatic bistable unit according to the present invention is also particularly adapted for use as a double pneumatic oscillator; in fact, it is only necessary to insert a pneumatic time-lag device between each outlet port and each pneumatic control chamber.

BRIEF DESCRIPTION OF THE DRAWING The invention will now be described more in detail with reference to a typical form of embodiment thereof which is illustrated diagrammatically in the single figure of the attached drawing showing a five-port bistable pneumatic valve unit according to the invention which is connected for operating as a double oscillator.

DESCRIPTION OF THE PREFERRED EMBODIMENT The bistable pneumatic valve unit illustrated in the drawing comprises a body 1 consisting preferably of plastic and made of a plurality of assembled sections, although it is shown in the form of a unitary block in order to simplify the drawing.

In the body 1 of substantially cylindrical configuration having a longitudinal center line x-x' and a transverse plane of symmetry y-y, a plurality of chambers are formed. These chambers comprise a central inlet or feed chamber 2, a pair of intermediate outlet chambers 3 and 4 disposed symmetrically in relation to said plane y-y', and a pair of terminal exhaust chambers 5 and 6 also disposed symmetrically in relation to said transverse plane y-y.

The central chamber 2 has its two longitudinal ends connected to an inlet passage 7 permitting the communication of this chamber 2 with an external pipe line 8 connected to a source of compressed air. Slidably mounted in said central chamber 2 is a free valve member 9 consisting of a very light-weight piston adapted to move freely in the axial direction within the chamber 2. This free valve member 9 comprising a cylindrical peripheral skirt 9a and a transverse central partition 91) divide the inlet chamber 2 into two sub-chambers 2a and 2d. This piston 9 acts as a valve member with respect to axial passages 10 and 11 concentric to said axis xx and connecting the central chamber 2 with the intermed ate outlet chambers 3 and 4, respectively. Cup-shaped fiap valves 12 and 13 are mounted for free axial movement in said chambers 3 and 4, respectively, and adapted to close exhaust passages 14 and 15 respectively, these last-named passages being provided for connecting the outlet chamber 3 to exhaust chamber 5, on the one hand, and the other outlet chamber 4 to exhaust chamber 6, on the other hand.

Besides, outlet ports 16 and 17 formed in the body 1 communicate the chambers 3 and 4 to outlet pipe lines 18 and 19, respectively.

The exhaust chambers and 6 communicates with the surrounding atmosphere via ports 21 and 22, respectively. A pair of axial and opposite push members 23 and 24 responsive to a pair of flexible membranes 25 and 26 are also disposed in said chambers 5 and 6, respectively. In the body 1 these membranes form on the one hand the aforesaid exhaust chambers 5 and 6 and on the other hand a pair on control chambers 27 and 28 to which a control pressure can be applied through control ports 29 and 31.

Now the operation of the bistable pneumatic valve unit will be described independently of its application to a double pneumatic oscillator to be described presently.

When the feed line 8 is connected to a suitable source of compressed air, the very light free valve 9, which cannot have a position of equilibrium centrally of chamber 2, is pressed by the compressed air against either of the connecting passages and '11. It will be assumed that immediately upon delivery of compressed air to chamber 2 the free valve 9 seats the passage 11. Now the two subchambers 2a and 2b of this central chamber 2 are subjected to the same feed pressure and since the pressure prevailing in sub-chamber 2a applies to the entire surface area of the central partition 9b of free valve 9, in contrast to the pressure prevailing in sub-chamber 2b which is exerted only against an annular portion of this partition, the resultant force or differential pressure causes the valve 9 to close the passage 11. But as the opposite passage 10 is not closed by the free valve 9, the outlet chamber 3 is pressurized and flap valve 12 seated to close the exhaust passage 14, so that compressed air flows via the outlet port 16 to the outlet line 18. On the other hand, as the flap valve is unseated, the chamber 4 and therefore the outlet line 19 remain at the atmospheric pressure.

Therefore, in the first stable position of the bistable pneumatic valve unit according to this invention the outlet line 18 is pressurized and the other pipe line 19 is at the atmospheric pressure.

If a control pressure is subsequently applied to chamber 27 via the control port 29, the membrane 25 of which the left-hand face (as seen in the drawing) receives the control pressure while its right-hand face is still at the atmospheric pressure, is distorted and moves to the right, so as to move the adjacent push member 23 in the same direction. Thus, the shank of this push member engaging freely the passage 14 unseats the flap valve 12. Under these conditions, the chambers 3 and 2a communicate immediately with the surrounding atmosphere and are thus drained, so that the pressure drops in these chambers. On the other hand, the other sub-chamber 2b, which can be drained only through the annular gap left between the peripheral cylindrical skirt 9a of free valve 9 and the inner wall of chamber 2, drains off at a slower rate and the pressure in this sub-chamber is still higher than that prevailing in the other sub-chamber 2a. Thus, a resultant force is exerted against the free valve 9 in the leftward direction, so that the passage 10 is again closed by this valve 9. At that time the communication between chamber 3 and the source of compressed air is discontinued, and the pressure in this chamber 3, and consequently in the outlet line 18, drops and is restored to the atmospheric value.

Simultaneously, the outlet chamber 4 is caused to communicate with the inlet chamber 2, whereby Chamber 4 is filled with compressed air. The pressure acting on flap valve 13 causes the latter to engage its seat and close the passage 15. Now compressed air flows through port 17 to outlet line 19. Under these conditions, the bistable pneumatic valve unit is in its second or other stable position in which the outlet line 19 is pressurized while the other outlet line 18 is at the atmospheric pressure.

If a control pressure is subsequently directed via port 31 into chamber 28, the same process takes place but in the reverse direction: thus, the membrane 26 moves the push member 24 to the left, as seen in the drawing, and the passage 15 is opened. Then, chamber 4 communicates with the atmosphere via this now open passage 15, and then the pressure differential building up in sub-chambers 2a and 2b causes the free valve 9 to close passage 11, so that the bistable pneumatic valve unit is restored to its first stable position.

According to modified forms of embodiment the control action exerted on push members 23 and 24 could take place in diffeernt ways, for instance by using mechanical, hydraulic or electric means,

Now, the manner in which the bistable pneumatic valve unit of this invention can be utilized for constituting a double oscillator will be described in detail. To this end, the outlet line 18 is connected to the port 29 of control chamber 27 through the medium of a time-lag device comprising an adjustable throttle 32, a non-return valve 33 and a capacity 34, the throttle 32 and non-return valve 33 being branched in parallel between the line 18 and capacity 34, the latter communicating on the other hand through a pipe line 35 with the control port 29. Similarly, the other outlet line 19 is connected to the control port 31 of control chamber 28 via another time-lag device comprising an adjustable throttle 37, a non-return valve 38 and a capacity 39, said throttle 37 and non-return valve 38 being branched in parallel between the line 19 and the capacity 39, the latter communicating via another line 41 with the control port 31.

The above-described double oscillator operates as follows: when the feed line 8 is connected to the source of compressed air one of the outlet pipe lines of the bistable pneumatic valve unit, for example line 18, is pressurized under the above-described conditions. The air pressure produced in the outlet line 18 is converted by the timelag device 32, 33 and 34 into a delayed control pressure transmitted to control chamber 27 via pipe line 35. This pressure is applied to the left-hand face of membrane 25 and this is attended by a substantially instantaneous tripping of the bistable pneumatic valve unit. Subsequently, it is the other outlet line 19 that becomes pressurized while the initial outlet line 18 is vented to the atmosphere. The non-return valve 33 permits of exhausting the capacity 34 as rapidly as possible. The other time-lag device 37, 38 and 39 converts the pressure produced in outlet line 19 into a delayed control pressure transmitted via line 41 to control chamber 28. The control pressure acting against the membane 26 causes in turn the tripping of the bistable pneumatic valve unit which is thus moved back from its second position to its first position.

The cyclic operation is continued in the above-described manner, the outlet lines 18 and 19 being pressurized by turns.

The time-lags introduced by the two time-lag devices 32, 33, 34, on the one hand, and 37, 38, 39, on the other hand, are independent of each other and can be adjusted separately by properly setting the adjustable throttles 32 and 37. According to a modified form of embodiment of this assembly these throttles 32 and 37 may have a constant cross-sectional passage area and the time-lag produced by these two time-lag devices may be adjusted by properly regulating the volumes of capacities 34 and 39.

One of the outlet lines, in this case pipe line 18, may be connected via adjustable throttle means 42 (in order to vary the air output) to a member to be supplied intermittently or periodically with compressed air, for example a breathing mask or the like.

Of course, the specific forms of embodiment described, illustrated and suggested herein are to be considered as exemplary and not as limiting the scope of the invention since many modifications and variations may be brought thereto without departing from the basic principles of the invention which are set forth in the appended claims. Thus, notably, the bistable cell according to this invention may also be operated by using a liquid fluid instead of a gas, and in this case the ports 21 and 22 are connected to return lines leading to a reservoir containing the liquid.

What I claim is:

1. Five-port bistable pneumatic valve unit comprising a body in which an inlet port connected to a source of compressed gas and first and second outlet ports and first and second exhaust ports are formed, characterized in that it comprises first and second outlet chambers connected directly to said first and second outlet ports and first and second exhaust ports, respectively, a cylinder-like feed chamber having two ends connected to said inlet port, a light-weight two faced, free piston slidably mounted in said cylinder-like chamber so as to divide the same into first and second separate sub-chambers, connected to said first and second outlet chambers via first and second passages, respectively, the two faces of said free piston acting as two valve elements for said first and second passages, respectively, first and second flap valves freely mounted in first and second outlet chambers respectively for closing said first and second exhaust ports respectively, first and second push members disposed externally of said first and second outlet chambers respectively and registering with said first and second exhaust ports so that they can project through said first and second passages and drivingly engage said flap valves in said outlet chambers for moving said flap valves away from said exhaust ports, and first and second members for actuating said first and second push members, respectively, and thus open said first and second flap valves, respectively.

2. A valve unit according to claim 1, characterized in that each push member actuating member comprises a membrane associated with a corresponding push member 6 and forming a control chamber to which a control pressure can be applied for moving said membrane and its companion push member towards the relevant flap valve for unseating said flap valve.

3. A valve unit according to claim 2, characterized in that two pneumatic time-lag devices, of which the time-lag constants are adjustable separately, are branched between the first and second outlet ports and the first and second control chambers formed by the membranes associated with said first and second push members respectively, whereby alternate opening of said flap valves effects movement of said free piston to alternately connect said first and second outlet ports to said inlet port.

4. A valve unit according to claim 3, characterized in that each time-lag device comprises a throttle and a nonreturn valve connected in parallel between an outlet line of the bistable valve unit and a capacity communicating on the other hand via a control line with the control chamber of said bistable valve unit.

5. A valve unit according to claim 4, characterized in that said throttle has a variable cross-sectional passage area.

6. A valve unit according to claim 4, characterized in that said capacity has a variable volume.

7. A valve unit according to claim 3, characterized in that one of the outlet lines of the valve unit is connected via an adjustable throttle to an apparatus fed periodically with gas under pressure, for example a breathing mask.

References Cited UNITED STATES PATENTS 1,529,384 3/1925 Adams 137-1l2 2,240,801 5/1941 Roy 91-268 2,601,531 6/1952 Kimmell 91-268 X 2,760,511 8/1956 Greelf 137624.14 X 3,504,692 4/1970 Goldstein 137624.14 X

ALAN COHAN, Primary Examiner US. Cl. X.R. 

